Internal combustion engines, such as automobile engines, include many mechanical elements such as pistons, shafts, and bearings, that rotate or slide against one another and that require proper lubrication to decrease friction, reduce wear and dissipate heat. For this reason, a lubricating oil system is provided for the engine to supply lubricating oil to these mechanical parts.
It is common practice today in designing internal combustion engines to provide for exhaust gas recirculation to reduce engine emissions. Experience has shown, however, that such engine designs tend to place increased stress on the engine lubricant. One of these stresses is the soot loading of the engine oil. Oil filters and recyclers of various designs have been an integral part of internal combustion engines as a way of removing contaminants from the engines recirculating lubricant to maintain the usefulness of the oil. Such devises, however, fail to rectify the soot loading problem. Presently, to prevent soot agglomeration and concomitant thickening of the engine oil, engine oils are formulated with dispersant viscosity modifiers to aid in the dispersion of the soot. While use of these additives increases lubricant life there still are soot levels in oils which result in loss of viscosity control.
Accordingly one object of the present invention is to provide improvements in controlling soot induced viscosity increase in lubricating oils.
Another object of the invention is to provide a method for reversing soot induced viscosity increase once it has occurred.
These and other objects of the invention will become apparent from what follows herein.